Comparison of effective collision strengths between different R-matrix calculations for transitions in the ground configuration 2s²2p² of S¹⁰⁺, where CKA92 refers to the interpolated data from R-matrix results for other ions in carbon-like sequence (Conlon et al. 1992), LB94 corresponds to the R-matrix work of Lennon & Burke (1994), ICFT denotes the present work. The transition is marked by i − j adjacent to the relevant set of curves. Note: the CKA92 data is extracted from the chianti v6 database. (Colour online.)